• Journal of Life Science
• /
• v.18 no.4
• /
• pp.522-529
• /
• 2008

High-temperature requirement A2(HtrA2) has been known as a human homologue of bacterial HtrA that has a molecular chaperone function. HtrA2 is mitochondrial serine protease that plays a significant role in regulating the apoptosis; however, the physiological function of HtrA2 still remains elusive. To establish experimental system for the investigation of new insights into the function of HtrA2 in mammalian cells, we first obtained $HtrA2^{+/+}$ and $HtrA2^{-/-}$ MEF cells lines and identified those cells based on the expression pattern and subcellular localization of HtrA2, using immunoblot and biochemical assays. Additionally, we observed that the morphological characteristics of $HtrA2^{-/-}$ MEF cells are different form those of $HtrA2^{+/+}$ MEF cells, showing a rounded shape instead of a typical fibroblast-like shape. Growth rate of $HtrA2^{-/-}$ MEF cells was also 1.4-fold higher than that of $HtrA2^{+/+}$ MEF cells at 36 hours. Furthermore, we verified both MEF cell lines induced caspsase-dependent cell death in response to apoptotic stimuli such as heat shock, staurosporine, and rotenone. The relationship between HtrA2 and heat shock-induced cell death is the first demonstration of the research field of HtrA2. Our study suggests that those MEF cell lines are suitable reagents to further investigate the molecular mechanism by which HtrA2 regulates the balance between cell death and survival.

• Korean Journal of Animal Reproduction
• /
• v.25 no.3
• /
• pp.219-225
• /
• 2001

To establish rabbit Embryonic Stem (ES) cells, rabbit one-cell embryos were collected and cultured in vitro to blastocysts. Blastocysts were co-cultured with mouse embryonic fibroblasts (MEF), rabbit embryonic fibroblasts (REF) or 570 cells expressing LIF (SNL). Although rabbit ES cells were isolated with low efficiencies, total 8 ES cell lines were kept in vitro with normal colony shape. The MEF was the best feeder for rabbit ES cell isolation in regard to growth rate and undifferentiated morphology. The doubling time of rabbit ES cells in MEF was about 84 hours and the undifferentiated morphology was maintained following passing and freezing processes. These rabbit ES cells were differentiated into embryoid body following the culture in the uncoated dishes, indicating that they were undifferentiated stem cells.

• The Journal of Korean Medicine
• /
• v.32 no.6
• /
• pp.10-17
• /
• 2011

Background: Vibration response imaging (VRI) is a new technology that records energy generated by airflow during the respiration cycle. Analysis of lung sound using VRI may overcome the limitations of auscultation. Objectives: To set a VRI standard for healthy Koreans, we conducted a clinical assessment to evaluate breath sound images and quantification in healthy subjects and compared the findings with reported breath sound characteristics. Methods: Recordings were performed using the VRIxp. Eighty subjects took a deep breath four times during a 12-second interval while sitting upright. The quantitative aspect was analyzed using the VRI quantitative lung data (QLD) for total left lung, total right lung and for six lung regions: left upper lung (LUL), left middle lung (LML), left lower lung (LLL), right upper lung (RUL), right middle lung (RML), right lower lung (RLL). The qualitative aspect was provided through image assessments by three reviewers. Results: In all regions the left lung had significantly higher QLD than the right lung (P<0.005, paired t-test). The inter-rater agreement was 0.78. 84% of the images were found normal by the final assessment. Among the 16% (n=13) of images with abnormal final assessment, the most common flawed features were dynamic image (77%, n=10) and maximum energy frame (MEF) shape (77%, n=10). No significant differences were found between males and females for QLD but there were significant differences in qualitative aspects including dynamic images, MEF shape, and missing LLL. Conclusion: The characteristics of healthy Koreans are similar to those of Western subjects reported previously. VRI is easy to use and objective, and so is helpful to diagnose patients with respiratory diseases and to monitor the progress of diseases after medical treatments.

• The Korean Journal of Physiology and Pharmacology
• /
• v.8 no.1
• /
• pp.33-41
• /
• 2004

We developed a cardiac cell model to explain the phenomenon of mechano-electric feedback (MEF), based on the experimental data with rat atrial myocytes. It incorporated the activity of ion channels, pumps, exchangers, and changes of intracellular ion concentration. Changes in membrane excitability and $Ca^{2+}$ transients could then be calculated. In the model, the major ion channels responsible for the stretch-induced changes in electrical activity were the stretch-activated channels (SACs). The relationship between the extent of stretch and activation of SACs was formulated based on the experimental findings. Then, the effects of mechanical stretch on the electrical activity were reproduced. The shape of the action potential (AP) was significantly changed by stretch in the model simulation. The duration was decreased at initial fast phase of repolarization (AP duration at 20% repolarization level from 3.7 to 2.5 ms) and increased at late slow phase of repolarization (AP duration at 90% repolarization level from 62 to 178 ms). The resting potential was depolarized from -75 to -61 mV. This mathematical model of SACs may quantitatively predict changes in cardiomyocytes by mechanical stretch.